Are all records synced each time or just those that have changed?

Subscriber:

Our system admin lead has raised some questions about how "intensive" the sync process could be if a customer has a large number of contacts on marketing lists (100,000 for example) and has used that list monthly for the last year.

If I have a marketing list with 100,000 contacts and I am syncing that marketing list nightly, will the app re-sync all 100,000 contacts regardless of whether or not there have been any changes? Is it deleting them from the marketing list and then re-adding them or is it just doing an update?

Also, if I've used the marketing list in 12 different campaigns in Constant Contact, will it resync all of the data in those 12 campaigns every night or just those that have changed? When it syncs is it doing an update on the campaign response record or is it deleting and re-inserting? Is there a period of time after a campaign was sent that it stops syncing responses?

Cazoomi:

After the initial Contact sync of your data, SyncApps will only look for and sync modified data. You can also hit the "Reset Sync Profile" at any time to do a complete resync.

But for Campaign Response Sync, currently, we sync all campaign data (that is sent within 30 days) every day. If the campaign response data already exists, SyncApps will update it. We might optimize SyncApps to sync updated data only.

SyncApps syncs campaign response until 30 days after the campaign response is sent.